Double walled insulated drinking vessels are commercially available from various vendors. There are also numerous U.S. Patents and published patent applications directed to doubled walled insulated drinking vessels, such as glasses, mugs, goblets, wine glasses and the like. See for example, U.S. Patents and published applications: Ser. No. 4,872,569 (Bolte); U.S. Pat. No. 5,090,213 (Glassman); U.S. Pat. No. 5,553,735 (Kimura); U.S. Pat. No. 5,839,599 (Lin); U.S. Pat. No. 6,050,443 (Tung et al.); U.S. Pat. No. 6,405,892 (Volan); U.S. Pat. No. 6,419,108 (Toida et al.); U.S. Pat. No. 6,921,179 (Ghanem); U.S. Pat. No. 7,306,113 (El-Saden et al.); D519,785 (Bodum); D526,848 (Bodum); D557,561 (Flowers et al.); 2004/0212120 (Giraud); 2005/0045643 (Ghanem); 2005/0173365 (McKnight); and 2005/0194340 (Huang).
While the insulated drinking vessels of the foregoing prior art may be generally suitable for their intended purposes, a need exists for a double walled drinking vessel which has a thin, drinking lip, yet which is simple in construction, easy to produce and which when completed exhibits structural integrity consistent with an integrally molded unit.
In my co-pending non-provisional application Ser. No. 14/665,223, filed on Mar. 23, 2015, entitled Insulated Doubled Walled Drinking Vessel And Method Of Making The Same, which in turn claims priority from provisional application Ser. No. 61/982,439, filed on Apr. 22, 2014 entitled Insulated Doubled Walled Drinking Vessel And Method Of Making The Same, both of which applications are assigned to the same assignee as this invention and whose disclosures are incorporated by reference herein, there is disclosed and claimed a double walled insulated drinking vessel formed of a pre-molded plastic inner vessel disposed within a pre-molded plastic outer vessel and whose top portions are joined together by in-situ molding a plastic ring thereon to provide the lip or rim for the drinking vessel. The in-situ molding of the ring on the top portions of the inner and outer vessels produces a non-superficial homogenous joint thereat. That joint is in the range of approximately 0.003 inch to 0.100 inch thick, with the resulting molded double walled drinking vessel exhibiting the same properties as if it had been molded as an integral unit at one time, e.g., it exhibits the same resistance to breakage or other damage at the location of the joint as remainder of the unit.
If the in-situ molding of the ring is accomplished to produce a joint having a thickness less than 0.003 inch, it may be susceptible to breakage. Thus, a need exists for a double walled drinking vessel whose drinking lip or rim is produced by in-situ molding a ring on the top of the inner and outer vessels to create a joint of less than approximately 0.003 inch and which is resistant to breakage at that joint. The subject invention addresses that need.